Why?

I heard a soldier say: "If we always knew why we kill, life wouldn't be possible any more." All right, it was in a movie, but the impact of these words does not change. Human beings kill: in wars, in peace, in the family, for seemingly understandable reasons, for no apparent reasons, sometimes even for fun. It seems that killing, nowadays, is considered an activity as any other, although not particularly appreciated. Maybe it was the same in the past. It seems so. I can't help wondering WHY. Why is there this... - I really don't know how to define it....- need, desire, acceptance, justification of such an action? Taking the life from a fellow human being can sometimes seem "justified" but, as the above mentioned soldier says, if people knew the real reasons, why they do it, they could not put up with the revelation. It would probably show something too difficult for them to accept about their real nature. No, I correct myself. It's not their real nature, because "nature" is never cruel for the fun of it. It would be an insight about what they have accepted to become, about what their conditioning has made of them. They would recognize that the life they are living and the actions they are committing are the consequence of an existence lived without awareness, an "unexamined  life", as Socrates used to say. He also added that such a life is not worth living at all. Too harsh a judgement?  It was his own. We are not here to condemn, only to observe and try to learn.